Exposures to low-level ionizing radiation: effects on biochemical and whole-body indices of growth in juvenile brook charr (Salvelinus fontinalis)

摘要

Exposure to ionizing radiation was used to alter gonadal growth in brook charr (Salvelinus fontinalis). To evaluate the possible effects of low-level doses of ionizing radiation on future seawater adaptability of brook charr, the physiological stateand growth performance of juvenile brook charr were examined for 15 months. Four groups of fish were exposed to different experimental doses of ionizing radiation at the hatching stage: 0 (control), 6.2, 7.8 and 11.4 Gy. Growth in length and weight andcondition factors of the irradiated groups were initially impaired compared with controls. Differences in growth were observed and were proportional to the irradiation dose. Initial growth delay in the irradiated groups was followed by compensatory growth of sufficient magnitude and duration that all groups reached similar weights and lengths by the end of the growth trial. Changes in the concentration of nucleic acids, protein and water content were evaluated at 3-month intervals (over 9 months) in thecontrol and 11.4 Gy groups. DNA content was consistently higher in the irradiated groups compared with controls (602.76 and 850.38μg/g wet tissue respectively). No difference in protein content in relation to fish weight was found between both groups during the freshwater growth period. Lipid analysis was performed on the final samples and was found to be significantly higher in the irradiated groups displaying catch-up growth (8.2 and 11.4% wet weight). RNA:DNA, RNA:protein and protein:DNA ratios were calculated.